1. Field of the Invention
The present invention relates to diazo photographic materials containing a novel coupler and to a process of developing diazo photographic materials, particularly to a process of developing diazo photographic materials for providing improved blue images.
2. Description of the Prior Art
The formation of dye images utilizing a photosensitive diazonium compound is generally conducted by a photographic process where the diazonium compound is uniformly distributed over the surface of a support, the diazonium compound layer is exposed imagewise to light to destroy the diazonium compound at the exposed areas, and then the photosensitive diazonium compound remaining at the unexposed areas of the surface is caused to undergo a coupling reaction with a so-called "coupler" capable of forming a dye by reaction with the diazonium compound under an alkaline atmosphere. Dye images are thus formed on the photographic material.
Since a diazo photographic process can be operated very simply, the duplication speed thereof is high, the image quality obtained by the process is good, the cost for the process is low, images of various colors can be obtained by the process and such a process is quite suitable as a document or image duplicating means. However, in conventional techniques for the process it is difficult or frequently impossible to form dyes having a desired color hue or color purity. This is because there are not sufficient kinds of proper diazonium compounds and couplers which are raw materials for dyes. Accordingly, it is necessary to increase the kinds of both materials so that the diazo photographic process can be applied to all the desired fields.